This isn't your actually literary fiction but - written 10(?) years ago, there's a young chap who's an alcoholic and looks like Robbie Williams. He gets in scrapes, trouble at work(?), goes on some kind of rampage and ends up pretending to be Robbie (?) or taking Robbie hostage (?). I don't think we ever know for sure it's Robbie but it's strongly implied.

The bit, for me, is the description of him buying a six-pack of lager and going home to his gf(?). He drinks a can (or two) on the walk. Offers her one, drinks another while pouring it, gives her a drink and glugs the rest. There's drugs too(?), and that's about all I remember.